Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B3885 02: Trailer Left Tail Lamp Circuit Short to GroundDTC B3885 04: Trailer Left Tail Lamp Circuit Open
DTC B3886 02: Trailer Right Tail Lamp Circuit Short to Ground
DTC B3886 04: Trailer Right Tail Lamp Circuit Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Trailer Left Tail Lamp | 3885 02 | 3885 04 | -- | -- |
Trailer Right Tail Lamp | B3886 02 | B3886 04 | -- | -- |
Circuit/System Description
The headlamp switch is supplied with ground at all times. When the headlamp switch is placed in either the park or low beam position, ground is applied to the tail lamp signal circuit to the body control module (BCM). The BCM sends this message to the trailer lighting converter. The trailer lighting converter then applies a voltage to the appropriate trailer tail lamp through there respective voltage supply circuits.
Conditions for Running the DTC
B3885 02, B3885 04, B3886 02 and B3886 04
The appropriate trailer tail lamp signal is active
Conditions for Setting the DTC
B3885 02 or B3886 02
The trailer lighting converter detects a short to ground on the control circuit.
B3885 04 or B3886 04
The trailer lighting converter detects an open control circuit.
Conditions for Clearing the DTC
The condition for setting the DTC is not longer present.
Action Taken When the DTC Sets
The appropriate trailer tail lamp is inoperative.
Reference Information
Schematic Reference
Trailer Connector/Provision Schematics
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, perform the appropriate Trailer Tail Lamp test. The appropriate trailer tail lamp should be ON/OFF
Circuit/System Testing
- Ignition OFF, test for less than 5 Ω between the X88 Trailer Connector terminal 3, 11, 13 and ground.
- Connect a test lamp between the appropriate X88 Trailer Connector terminal listed below and ground.
- Command the appropriate Trailer Tail Lamp Active / Inactive test with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all the circuits test normal, test the appropriate tail lamp circuit at the trailer.
| ⇒ | If greater than the specified value, test the appropriate ground circuit for an open/high resistance. |
| • | X88 Trailer Connector terminal 5 |
| • | X88 Trailer Connector terminal 7 |
| ⇒ | If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K68 Trailer Lighting Converter. |
| ⇒ | If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K68 Trailer Lighting Converter. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for trailer lighting converter replacement, setup and programming
